Polyacrylonitrile fibre for technical purposes. Part I. Kinetics of acrylonitrile and methylacrylate
Kinetics of copolymerization of acrylonitrile (AN) and methylacrylate (MA) in an aqueous solution of NaSCN with azodiisobutyronitrile (AIBN) as aninitiator has been investigated in order to determine the basic parameters of the system. The reaction kinetics has been studied at total monomer concentration of 1.75—3.3 mol/dm3, while the AIBN concentration range was (3.22—12.0)10'3 mol/dm3, at 80°C. The reaction order of 1.57 with respect to monomer and 0.48 with respect to initiator has been determined, as well as the polymerization rate constant of 3.6T0'3 dm3/(mols). The constantratio Kp/Kt0 5 of 0.36 and the constant of chain activity transfer to MA of 0.98T0'4 have been calculated on the base of kinetic data. At the optimal reaction conditions, as in the laboratory-scale investigations, a copolymer of AN:MA (98:2) has been synthesized in a pilot-plant and the copolymer solution as obtained in ater/NaSCN solution has been used for a direct fiber spinning process. The corresponding dynamic viscosity of the polymer spinning solution containing 11% polymer has been previously determined (38.5 Pas). An acrylic fiber of 2.4 dtex has been spun with the tensile strength of 44 cN/dtex and it could be classified in a group of technical acrylic fibers.
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